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Re: Active issue rdfms-graph; formal description of properties of an RDF graph

From: Dan Connolly <connolly@w3.org>
Date: Thu, 11 Oct 2001 17:30:26 -0500
Message-ID: <3BC61D82.26BA1DA@w3.org>
To: Pat Hayes <phayes@ai.uwf.edu>
CC: w3c-rdfcore-wg@w3.org, pfps@research.bell-labs.com
Pat Hayes wrote:
> After getting this wrong several times,

Now there's a red flag right there: the guy who has
been doing symbolic logic for breakfast since about
the time I was born got this wrong several times.
And even with all these contortions and special
cases, RDF/XML 1.0 syntax *still* can't serialize
all the graphs of this form.

I suggest, again, the following simple abstract syntax:

  An RDF graph is a set of triples <S, P, O>; each
  of S, P, O is a term; a term is either an absolute
  URI reference, a bNode, or a literal.


The model theory straightfowardly applies to this liberal
syntax, I believe. Regarding scope, I think it's straightforward
to treat bNodes the way local variables are treated in
traditional logical syntax: you rename them as necessary
when you merge graphs.

After thinking for a while[27Sep] about the question of whether
the formalism for RDF graphs should be limited by RDF/XML 1.0
syntax, I've come to the pretty firm conclusion that no,
there's no reason we should have to redo the RDF Core model
theory when we revisit the design of RDF syntax. In fact,
this liberal abstract syntax should go a long way toward
shaping the design of new RDF concrete syntaxes.


> here's an attempt at a formal
> definition of an RDF graph. This is worded to make it align naturally

"naturally". Hmm... that's a stretch!

> with the Ntriples syntax.
> -----
> An RDF graph <N,E,oo,ss,gl> is a special labelled directed
> multigraph, consisting of:

Dan Connolly, W3C http://www.w3.org/People/Connolly/
Received on Thursday, 11 October 2001 18:30:32 UTC

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